In this paper we select restore silty clay as test soil samples, investigate dynamic and static mechanical properties of soil mass under circulating load, and static strength weakening of law by using the indoor static triaxial test system, and take into account the confining pressure, consolidation ratio, frequency and dynamic stress ratio and cyclic number five factors' influence on static strength. The experiment shows that compared with the original soil of soil under cyclic loading total strength may increase or reduce, and the pore pressure at the time of shearing will be larger than the pore pressure at the time of shearing. It can be unified that all effective strength of soil under cyclic loading are reduced. The dynamic elastic strain and dynamic elastic pore pressure are introduced through the dimensionless treatment of strength. The dynamic elastic strain and effective strength ratio are determined. The relationship between dynamic elastic pore pressure and effective strength ratio accords with exponential model, and it is suitable for the attenuation coefficient and elastic strain, attenuation coefficient and the logarithmic function of pore pressure dynamic elastic model.